1. Field of the Invention
The present invention relates generally to structural ceramics. More specifically, the present invention relates to ceramic foams saturated or sheathed in polymeric materials to provide an energy absorbent structural material; as well as a method of making the same.
2. Description of the Related Art
There are known in the ceramic arts open-celled ceramic foams such as discussed in applicant's prior application Ser. No. 486,801 filed Feb. 26, 1990, now abandoned. These foams are currently in use, as filter media, such as those available from Consolidated Aluminum of St. Louis, Mo. These open-cell ceramic foam bodies are manufactured by impregnating an open-cell polyurethane or other organic foam with a ceramic slurry. The excess slurry is then squeezed out and the impregnated foam is fired to decompose the polyurethane foam, resulting in a pseudo-positive ceramic replica of the original foam body. The term pseudo-positive is used because the actual legs, or structural members, of the ceramic foam are hollow and represent only that part of the ceramic which has coated the underlying organic foam. This ceramic foam has high compressive strength due to the inherently high compressive strength of ceramic materials and owing to its three dimensional repeating dodecahedral structure.
Further desirable characteristics of ceramic materials for use in structural applications include their low reactivity with the environment, their relatively low costs and abundant supply of raw materials, and their relatively light weight, especially when considered in the present instance of foam bodies.
While the aforedescribed ceramic foam body with hollow legs is admirably suited to its intended task as a filter media, it would need certain improvements to be used as a skeletal structure for structural members owing to its brittleness, a property of most ceramics; its susceptibility to surface abrasion; and would require suitable means for anchoring mechanical fasteners or the like to the foam. Accordingly, it would be desirable to produce a structural material having a low-weight, high-compressive strength, skeleton of ceramic foam which is strong, surface-abrasion resistant, and which easily accepts fastening means so as to be used in a variety of structural applications. Further it may be desirable in certain applications to provide a ceramic foam skeletal structure having solid-legs rather than the aforedescribed hollow legs for increased structural integrity.